Dried vegetables are important articles of commerce and are used extensively in the food industry in soups, casseroles, dried packaged foods of various types and many other processed food applications.
Conventional dried vegetables are usually prepared from blanched pieces of vegetable which are dried in hot air to a moisture content of about 5%. These vegetable pieces take a considerable time to rehydrate, in the order of 5 to 20 minutes depending on the dimensions of the piece.
The current consumer demand for convenience food products has created a requirement for many types of packaged "instant" foods. These vary for example from soup mixes that can be used after rehydration for 60 seconds with the addition of boiling water, to products with stove-top or microwave cook-times of two to five minutes.
A range of freeze-dried vegetable pieces is available with rapid rehydration times. These suffer from the disadvantage of being very expensive and very fragile. In addition, in mixes, because of their low bulk density, they tend to float on top of the product rather than incorporate within it as would a fresh vegetable.